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A SIMPLE PRIMER ON RADIATION

By Alan Cocchetto, NCF Medical Directorę2010

From Winter 2010-2011 Forum

Basically there are two different types of radiation. These are known as ionizing and non-ionizing radiation. By definition, ionizing radiation includes such things as electromagnetic radiation, X-rays, gamma-rays as well as particulate radiation, such as neutrons and alpha-particles. Ionizing radiation possesses sufficient energy to induce ionization of atoms or molecules that are capable of removing electrons from their outermost orbit. Ionizing radiation is differentiated on the basis of their linear energy transfer, or LET, which refers to the amount of energy deposited by a particular type of radiation per unit of path length. The density of the ionization separates low from high LET. High LET is more efficient in producing biological damage versus low LET. By comparison, non-ionizing radiation refers to any type of electomagnetic radiation that does not carry enough energy to ionize atoms or molecules. Examples of this include near ultra-violet (UV), visible light, infrared, microwave, radiofrequency radiation etc.

Protecting an individual from the initial transfer of radiation energy, which occurs in a fraction of a second, is virtually next to impossible due to the speed of the energy transfer. As such, high LET radiation produces direct damage (think Nagasaki and Hiroshima bombings) which is difficult to modify. As a consequence, much scientific effort has focused on altering radiation injury due to low LET exposure.

Anyone who has read the medical literature on CFIDS/ME knows that this disease is associated with excessive reactive oxygen species (ROS) and. in fact, some physicians have recommended the use of various antioxidants to combat ROS formation or to "soak up" ROS by-products. Well, exposure of humans to ionizing radiation results in not only the formation of ROS but also the formation of reactive nitrogen species (RNS). Both ROS and RNS inflict damage to various biological macromolecules like DNA, lipids and proteins that are present in the cell. The effects of ionizing radiation at the cellular level include the following:

  • Increased ROS generation
  • Changes in membrane potential
  • DNA damage
  • Decreased ATP production
  • Release of cytochrome C
  • Calcium release from mitochondria
  • Increased apoptosis and cell death

Why does ionizing radiation cause this type of oxidative damage to the cell membrane lipids and proteins? This is largely due to remarkable changes and disturbances in the biochemical as well as the physiologic function of the cell. Simply stated, the cell becomes seriously damaged and therefore its function is compromised. It should be noted that ionizing radiation produces both direct as well as indirect negative effects on the cell. Both of these are damaging to the cell which subsequently leads to cell death and potentially to death of the organism itself.

When an individual is exposed to ionizing radiation, the health effects are classified as either probabilistic or deterministic. These are best understood through the use of examples. For example, the probability of developing cancer several years after exposure versus deterministic effects which can include effects such as hematologic deficiencies (bone marrow suppression), skin damage, loss of fertility, etc. Exposed individuals may develop radiation sickness or they may develop radiation injury. Unfortunately, ionizing radiation can activate oncogenes (genes that are mutated or expressed at high levels to turn a normal cell into an abnormal one) through a number of mechanisms that include chromosomal damage. A common clinical endpoint of chromosomal damage is cancer.

The intention of this simple primer is to demonstrate that the health effects of ionizing radiation are very serious and can prove ultimately to be fatal. Since CFIDS/ME has already been shown to be directly associated with ionizing radiation exposure, it is imperative to consider its role in a subgroup of patients with this disease.

Though the NCF's scientific research is on-going, evidence is suggestive of direct internal ingestion of one or more radionuclides associated with water and/or food sources. A future article will address several key markers in CFIDS/ME and their direct relationship to ionizing radiation.


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